if you're taking blood thinner, for example, a lot of these medications interfere and make you bleed. ginger, right? causes your heart to beat irregularly. >> i think about ginger, taking it for an upset stomach. >> right. but meanwhile, there are other products in there. jenna: that's mixed sometimes with natural remedies and as a consumer, you may not know that. >> you don't get a label half the time. jenna: on the screen we have a few products. fish oil, people tell you to take it for all sorts of things, st. john's wort to help you. >> fish oil, new studies are showing it causes deadly prostate cancer. you don't want to take that. if anything, no more than two servings of fish a week. you don't know what's in it. ginseng makes you bleed.